The DetectPlagiarism command compares essays using the SimilarityScore command and returns list indicating the entries that scored above the specified threshold.  

Instead of passing in the essays to be compared, a similarity matrix like one generated by the SimilarityScore command can be pregenerated and passed in.  

The DetectPlagiarism command recommends essays that are so similar that they are likely to be copies of each other, or contain sub-text that is copied.  This is a probabilistic measure and does not guarantee that the similar essays are indeed copies of each other or were copied from the same source.  

If no two essays exceed the threshold in the similarity comparison, then an empty list, $\left[\right]$, will be returned.  Otherwise, a list of lists will be returned.  Each sublist will contain two integer indices and the similarity score.  For example, [4,5,.695] indicates that essays 4 and 5 received a similarity score of .695, and are therefore likely to be copied from the same source, or copies of each other.  

The default threshold is .35, and the default similarity metric is the BinaryJaccardCoefficient.  Similarity scores flagged will range from .35 to 1, where numbers closer to 1 indicate more similarity. A score of 1 indicates identical copies.

This function is part of the EssayTools package, so it can be used in the short form DetectPlagiarism(..) only after executing the command with(EssayTools). However, it can always be accessed through the long form of the command by using EssayTools[DetectPlagiarism](..).

$\mathrm{with}\left(\mathrm{EssayTools}\right)\:$

$\mathrm{sample}≔\left[''a\; b\; c\; d''\,''e\; f\; g\; h''\,''a\; b\; y\; z''\,''a\; i\; j\; k''\,''a\; b\; j\; d''\right]\:$

$\mathrm{DetectPlagiarism}\left(\mathrm{sample}\right)$

$\left[\left[1\,5\,0.6000000000\right]\right]$

$\mathrm{SimilarityScore}\left(\mathrm{sample}\left[1\right]\,\mathrm{sample}\left[5\right]\right)$

$\left[\begin{array}{c}0.6000000000\end{array}\right]$

$\mathrm{altScores}≔\mathrm{SimilarityScore}\left(\mathrm{sample}\,\mathrm{methods}=\left[\mathrm{CosineCoefficient}\right]\right)$

$\mathrm{altScores}≔\left[\begin{array}{ccccc}1.000000000& 0.& 0.5000000000& 0.2500000000& 0.7500000000\\ 0.& 1.000000000& 0.& 0.& 0.\\ 0.5000000000& 0.& 1.000000000& 0.2500000000& 0.5000000000\\ 0.2500000000& 0.& 0.2500000000& 1.000000000& 0.5000000000\\ 0.7500000000& 0.& 0.5000000000& 0.5000000000& 1.000000000\end{array}\right]$

$\mathrm{DetectPlagiarism}\left(\mathrm{altScores}\,'\mathrm{threshold}'=0.45\right)$

$\left[\left[1\,3\,0.5000000000\right]\,\left[1\,5\,0.7500000000\right]\,\left[3\,5\,0.5000000000\right]\,\left[4\,5\,0.5000000000\right]\right]$

$\mathrm{Answer1}≔''An\; abacus\; is\; a\; counting\; device\; consisting\; of\; a\; frame\; that\; holds\; rods\; on\; each\; of\; which\; a\; specific\; number\; of\; beads\; are\; free\; to\; move\; in\; such\; a\; way\; that\; each\; configuration\; of\; beads\; represents\; a\; unique\; number\; by\; a\; form\; of\; place-value\; notation.\; For\; example,\; if\; each\; rod\; holds\; nine\; beads,\; the\; successive\; rods\; could\; represent\; units,\; tens,\; hundreds,\; etc.,\; in\; the\; decimal\; counting\; system,\; and\; the\; number\; represented\; by\; a\; particular\; configuration\; would\; depend\; upon\; how\; many\; beads\; are\; moved\; towards\; the\; horizontal\; bar.\; However,\; the\; Chinese\; abacus\; uses\; a\; more\; complex\; system.\; Each\; rod\; contains\; five\; beads\; and\; two\; beads\; separated\; by\; a\; horizontal\; bar.\; The\; five\; beads\; represent\; units,\; tens,\; hundreds,\; etc.\; and\; the\; two\; beads\; represent\; fives,\; fifties,\; five\; hundreds,\; etc.''\:$

$\mathrm{ReplaceWords}≔''An\; abacus\; is\; a\; machine\; for\; counting\; made\; up\; of\; an\; enclosure\; that\; holds\; bars\; on\; each\; of\; which\; a\; determined\; number\; of\; beads\; are\; free\; to\; move\; in\; such\; a\; way\; that\; each\; arrangement\; of\; beads\; represents\; a\; different\; number\; by\; a\; form\; of\; place-value\; notation.\; For\; example,\; if\; each\; bar\; has\; nine\; beads,\; the\; successive\; bars\; could\; indicate\; units,\; tens,\; hundreds,\; etc.,\; in\; the\; decimal\; counting\; system,\; and\; the\; number\; represented\; by\; a\; particular\; arrangement\; would\; depend\; upon\; how\; many\; beads\; are\; moved\; towards\; the\; horizontal\; bar.\; But,\; the\; Chinese\; abacus\; uses\; a\; more\; complicated\; system.\; Each\; bar\; has\; five\; beads\; and\; two\; beads\; divided\; by\; a\; horizontal\; bar.\; The\; five\; beads\; denote\; units,\; tens,\; hundreds,\; etc.\; and\; the\; two\; beads\; denote\; fives,\; fifties,\; five\; hundreds,\; etc.''\:$

$\mathrm{TextAdded}≔''The\; abacus\; is\; an\; ancient\; machine\; dating\; back\; thousands\; of\; years.\; An\; abacus\; is\; a\; counting\; device\; consisting\; of\; a\; frame\; that\; holds\; rods\; on\; each\; of\; which\; a\; specific\; number\; of\; beads\; are\; free\; to\; move\; in\; such\; a\; way\; that\; each\; configuration\; of\; beads\; represents\; a\; unique\; number\; by\; a\; form\; of\; place-value\; notation.\; For\; example,\; if\; each\; rod\; holds\; nine\; beads,\; the\; successive\; rods\; could\; represent\; units,\; tens,\; hundreds,\; etc.,\; in\; the\; decimal\; counting\; system,\; and\; the\; number\; represented\; by\; a\; particular\; configuration\; would\; depend\; upon\; how\; many\; beads\; are\; moved\; towards\; the\; horizontal\; bar.\; However,\; the\; Chinese\; abacus\; uses\; a\; more\; complex\; system.\; Each\; rod\; contains\; five\; beads\; and\; two\; beads\; separated\; by\; a\; horizontal\; bar.\; The\; five\; beads\; represent\; units,\; tens,\; hundreds,\; etc.\; and\; the\; two\; beads\; represent\; fives,\; fifties,\; five\; hundreds,\; etc.\; Even\; today\; people\; still\; use\; the\; abacus\; for\; counting.''\:$

$\mathrm{IndependentAnswer}≔''An\; abacus\; is\; a\; device\; used\; for\; counting.\; It\; is\; made\; up\; of\; rods\; and\; beads.\; Each\; rod\; has\; 9\; beads\; and\; represents\; a\; digit\; in\; a\; number.\; The\; rightmost\; rod\; is\; the\; ones\; column,\; the\; rod\; adjacent\; to\; that\; is\; the\; tens\; column,\; the\; next\; rod\; is\; the\; hundreds\; column,\; etc.\; Each\; bead\; can\; slide\; up\; and\; down\; the\; rod.\; The\; number\; of\; beads\; moved\; to\; the\; top\; of\; the\; rod\; indicates\; the\; digit\; for\; that\; column.\; For\; example,\; an\; abucus\; with\; 7\; rods\; would\; represent\; the\; number\; 123\; by\; moving\; one\; bead\; to\; the\; top\; of\; rod\; \#5,\; two\; beads\; to\; the\; top\; of\; rod\; \#6,\; and\; three\; beads\; to\; the\; top\; of\; rod\; \#7.''\:$

$\mathrm{DetectPlagiarism}\left(\left[\mathrm{Answer1}\,\mathrm{ReplaceWords}\,\mathrm{TextAdded}\,\mathrm{IndependentAnswer}\right]\right)$

$\left[\left[1\,2\,0.6951219512\right]\,\left[1\,3\,0.8607594937\right]\,\left[2\,3\,0.6483516484\right]\right]$

The EssayTools[DetectPlagiarism] command was introduced in Maple 17.

For more information on Maple 17 changes, see Updates in Maple 17.